Pressurized canisters that dispense fluid are known in the art. The fluid is expelled through a dispensing valve and expansion nozzle to atmospheric pressure.
The traditional dispensing system for such a pressurized canister is a normally-closed, push-to-open, release-to-close valve. The user interaction with this valve is inexact, and the system depends on the user to meter and dispense the amount of liquid by manually opening the valve until the desired amount of liquid is dispensed and then releasing the valve. To add to the imprecision of the dispensed amount of liquid, the volume of the liquid may change during and after expulsion, making the process of judging “visually” the amount of liquid dispensed difficult during the user's interaction with the valve. If the user holds the valve open too long, he dispenses too much liquid.